Inside Donato’s House of Greens in Woodbury, Connecticut, are rows of vibrant green buttercrunch lettuce. They aren’t much different from other lettuce heads, except they are ready for sale in only four to five weeks rather than 60 days, come with an attached dirt-like root bulb for longer storage life and are grown without soil. Since 2008, owner and grower Joe Donato has been practicing hydroponics, or the process of growing plants in nutrient-rich solutions with or without a medium or substrate (peat, sand, gravel or perlite) to support the roots.

“We always like to try new things,” says Donato. “This allows us to grow in the winter.”

Hydroponics refer to a range of water-based cultures that deliver nutrients to plants. The nutrient solutions can include inorganic salt fertilizers and semi-soluble organic materials such as bat guano, bone meal and fish emulsion. In “pure” hydroponics, the plant depends on the roots alone to provide all the nutrients. In hydroponics systems that utilize substrates, it’s easier to maintain the right balance of nutrients.

Donato designed his own system: household gutters covered in foam board with holes to support the plants, air pumps to provide a steady stream of nutrient solution and a combination of natural and supplemental light sources. His plants are supported by Rockwool, or melted volcanic rock that is spun, compressed, formed into a solid mass and cut into blocks.

“Regardless of how the nutrients get into the root zone, they have to be in soluble form for the roots to take them up,” says George Elliott, associate professor of horticulture at the University of Connecticut.

Fruits and vegetables grown in soil depend on organisms to break down nutrients. “Even if you put in an organic fertilizer, it has to be degraded by the microbes in an inorganic form for the plants to absorb it,” says Louis D. Albright, professor of biological and environmental engineering at Cornell University.

Without soil, there is little to no microbial activity, so the plants depend on direct nutrients from nutrient solutions. And because hydroponics occur in a highly controlled space and microbial activity is at a minimum, pesticides, insecticides and herbicides are not needed.

Albright also serves as the director of the Controlled Environment Agriculture program at Cornell. There, he grows vegetables in a floating hydroponics system, in which plants are put into holes in Styrofoam boards and the roots are floated and grown in a nutrient solution.

The program was started as an initiative by the New York State Energy Office to develop new growing methods that could ease dependence on diesel and oil. The facility can already grow approximately 20 times as much lettuce per square foot as many California lettuce fields. Growing in a greenhouse cuts down on energy transport, land use and natural resource costs, especially during the Northeast’s colder months when food imports increase.

And hydroponics make it possible to grow in urban areas. Britta Riley, an artist who founded windowfarms.org, was active in rooftop gardening but recognized its challenges. “Most of the buildings in New York City right now will not handle the weight of a regular green roof, much less one that grows vegetables,” says Riley. “When you deal with hydroponics, you can grow a lot of food without having such a high weight load.”

Riley created a hydroponic farm in her apartment window that utilized recycled water bottles, inexpensive air pumps and other supplies from her local hardware store. It supported 25 plants, including bok choi, lettuce, tomatoes and peppers.

Today, windowfarms.org has 8,000 registered users who can download free how-to instructions for homemade hydroponic systems, and approximately 200 individuals who participate in what Riley calls “Research and Do-It-Yourself.” “These things will not start to take root until people really want sustainable solutions, good nutrition and local food,” Riley says.

Albright suggests that hydroponic products are “beyond organic,” because they follow a rigorous food safety management system that addresses production, handling, manufacturing and distribution, or what the Food and Drug Administration calls Hazard Analysis and Critical Control Points.

“If you follow the protocol, it has a high probability of food safety,” he says. “And [hydroponically grown] food does not have to be washed, so we can produce lettuce that does not have to be run three times through a chlorine solution to remove disease organisms.”

But hydroponics will need specific standards to gain organic certification. In January 2010, the National Organic Standards Board submitted a recommendation of production standards for container and soil-less growing after it was discussed that hydroponics “cannot be classified as certified organic methods due to their exclusion of soil-plant ecology.” The document outlines proposed requirements for greenhouse operations, including management and reuse of nutrients, erosion control and light source use.

UConn’s Elliott says efforts are already underway to develop a system of best management practices. “I don’t see any need for government regulation,” he says. “Do we need to have a set of criteria that can be used to engage questions about sustainability and any environmental impact of these practices? Yes, we do.”